The present invention relates to the reaction of isobutene by contact with perfluorosulfonic acid resins. More particularly the present invention relates to the hydration and polymerization of isobutene or the dehydration of t-butanol employing these resins.
The acid catalysis of the reaction of isobutene and water to produce t-butanol and/or dimers, trimers, tetramers and other oligomers is well known. More recently acid ion exchange resins have been used as the catalysts, e.g., British Pat. Specification 1,390,164 and 1,396,488, where the reaction of propylene and water was illustrated in a fixed bed acidic ion exchange resin.
For t-butanol production fixed bed procedures have been proposed as the most desirable arrangement because of the simplicity of operation, i.e., water and isobutene are passed over the catalyst, the phases separated and t-butanol separated from the organic phase and/or the water phase. A rapid increase in by-product formation has characterized such operation. At the beginning of the process, the reaction proceeds as expected, with high selectivity for the production of t-butanol. Side reactions begin and increase as the reactions proceed, with a substantial reduction of t-butanol formation. The side reactions include particularly polymerization, which is uncontrolled and from which result diisobutene, triisobutene, higher oligomers, and codimers of isobutene and n-butenes.
The formation of diisobutene and triisobutene may not be particularly undesirable since these materials are of commercial interest. The higher oligomers, however, are substantially waste and in some cases are dark, gummy materials. Furthermore, the uncontrolled side reaction is a detriment, since product distribution cannot be adjusted as desired. It should also be noted in the prior art that by-product selectively could be reversed only by the secession of the reaction, back washing of the catalyst with water or replacement of the catalyst.
U.S. Pat. No. 3,328,781 issued to Kronig, et al employed a fluidized system. t-Butanol is recovered by distillation from the hydro-carbon phase and the water - resin phase is recycled to the reactor. The selectivity to t-butanol remained high.
A fluidized system is inherently less desirable because the catalyst is mixed into the reactants and some portion may remain in the hydrocarbon fraction, requiring an additional separation; and attritive action of the fluidized bed may cause disintegration of the catalysts.
The present invention employs an acid resin which may be employed as granules or particles in a prior art fixed or fluidized bed, however, the perfluorosulfonic acid resins are readily formed into stable films or membranes which have permeability properties which make them adapted to a novel method of reacting isobutene to produce t-butanol and polymers or dehydrating t-butanol to produce isobutene.